This application is based on and claims priority to Japanese Patent Application No. 2001-327636, filed Oct. 25, 2001, the entire contents of which is hereby expressly incorporated by reference.
1. Field of the Invention
The present invention relates generally to an engine fuel delivery system for an engine, and more particularly to an improved fuel injector and cylinder head assembly allowing for a more compact engine design and stratified-charge operation.
2. Brief Description of Related Art
One important characteristic of an engine is its output power. A great deal of engineering is involved with improving the output power of an engine. In addition, an equal amount of care is often involved with maintaining the output power when developing and installing additional engine systems and components.
One particularly sensitive system is the air induction system. Typically, induction systems for engines designed for outboard motor use include a plenum chamber, a throttle body, and an intake passage. In addition, typical engines include a fuel delivery system which cooperates with the air induction system to deliver an air/fuel charge to a combustion chamber of the engine. The fuel delivery system typically comprises a fuel tank, one or more fuel conduits, and a fuel injector for those engines using a direct injection method of delivering fuel to a combustion chamber. The fuel delivery system commonly includes fuel injectors mounted in close proximity to an engine body to inject fuel directly into a cylinder head or into an intake passage that communicates with the combustion chamber.
These two cooperating systems must be configured to deliver air and fuel to the combustion chamber. However, these systems must be carefully engineered so as to reduce the flow resistance in each of these systems, which can have an adverse effect on the engine efficiency, and hence, the output power.
Perhaps the greater importance is the configuration of the air induction system and, particularly, the routing of the air intake pipes, intake manifold, and intake runners. It is preferable that the air intake pipes have a low flow resistance, and hence it becomes undesirable for the intake pipes to be bent or tapered to avoid interference with other engine accessories, which can increase the intake resistance, and therefore, result in the reduction of engine output power.
Many of the engine accessories can be beneficially located to provide for a smoother operating and more efficient engine. Unfortunately, the desired location of these accessories can interfere with the preferred routing of the induction system components. While the engine accessories can be mounted in various locations around the engine, their location must be balanced against the desire to maintain a compact engine.
Due to compact engine design demands, fuel injectors are often placed close to the outside of the engine body. However, heat transfer issues can arise when the fuel injectors are placed in proximity to the engine body, and heat generated within the engine body from the combustion process flows to the fuel injectors and heats the fuel before it is injected into the combustion chamber, which can reduce the engine efficiency.
One aspect of the present invention includes the realization that the induction system components can be beneficially configured and routed to provide a low flow resistance while allowing for a sufficient space to mount auxiliary components in close proximity to the engine body thus providing a compact engine arrangement. An additional aspect includes the realization that the fuel injectors can be located in close proximity to the engine body and the heat transfer reduced by indirect cooling from the adjacent air induction system components.
In accordance with another aspect of the invention, a four-cycle engine for use in an outboard motor comprises a cylinder body defining at least one cylinder bore therethrough, a cylinder head assembly connected to the cylinder body, and a piston disposed within the cylinder bore. The cylinder body, the cylinder head assembly, and the piston cooperate to define a combustion chamber.
At least one intake passage is formed in the cylinder head assembly. A crankshaft is rotatably coupled to the piston. Additionally, a fuel injector has a longitudinal axis and is arranged to directly inject fuel into the combustion chamber. The fuel injector is additionally disposed between the intake passage and an imaginary line extending laterally from a junction between the cylinder body and the cylinder head assembly when viewed from a direction along an axis of the crankshaft. In this orientation, the fuel injector axis is arranged to be substantially parallel to the intake passage defined by the cylinder head assembly.
An induction system is connected to the intake passage and extends generally laterally from the cylinder head assembly and then along a side of the cylinder body at a distance from the cylinder body. An auxiliary component is disposed in a space formed between the induction system and the cylinder body.
The cylinder head assembly can include at least two intake passages that are disposed next to each other in a direction that extends generally parallel to the axis of the crankshaft, and the fuel injector can be disposed in a vicinity between the two intake passages.
The auxiliary component disposed in the space formed between the cylinder body and the induction system can be a fuel vapor separator, a throttle link mechanism, a battery, a starter motor, an oil filter, or a fuel cooler or any combination thereof, including additional auxiliary components not specifically listed.
According to one embodiment in which the cylinder body defines a plurality of cylinder bores arranged in a V-shape, the induction system is disposed on the exterior of the V-shape.
According to another aspect, a four-cycle engine comprises an engine block defining a cylinder bore and has a cylinder head assembly attached to the cylinder block to close one end of the cylinder bore. The cylinder head assembly includes at least one intake passage. A piston is positioned within the cylinder bore and is arranged to reciprocate along a cylinder axis so as to define a variable volume combustion chamber together with the cylinder bore and the cylinder head. The intake passage of the cylinder head communicates with the combustion chamber through at least one intake port. A fuel injector is configured to inject fuel directly into the combustion chamber and is disposed between the engine body and the intake passage. The fuel injector preferably has a longitudinal axis that is oblique to the cylinder axis.
The fuel injector can be positioned between the intake passage and a plane extending laterally from a junction of the engine body and the cylinder head assembly. The fuel injector longitudinal axis can be arranged generally parallel to a flow axis of the intake passage.
According to yet another aspect, an engine having an engine body comprises at least one variable volume combustion chamber defined in part by a head of a moveable piston. At least one intake port opens into the combustion chamber. An induction system communicates with the intake port through at least intake passage formed in a cylinder head of the engine body. An intake valve is moveable to regulate communication between the induction system and the combustion chamber through the intake port and the intake passage. The fuel delivery system has at least one fuel injector arranged to lie generally parallel to the intake passage for injecting fuel into the combustion chamber. The fuel injector is preferably positioned between the engine body and the intake passage. The fuel injector can be oriented such that the fuel injector injects fuel into the combustion chamber toward the head of the piston.
The engine body can comprise a crankcase, a cylinder block, and a cylinder head assembly. In this embodiment, the induction system can extend away from the cylinder head assembly, along a side of the cylinder block, and toward the crankcase.
According to another aspect, an outboard motor comprises an engine including an engine body, the engine body cooperating with at least one reciprocating piston to define at least one combustion chamber. An induction system is configured to guide air to the combustion chamber through at least a pair of intake ports. At least one fuel injector is configured to inject fuel for combustion in the combustion chamber. The fuel injector is preferably mounted between the engine body and at least a portion of the induction system and is generally in between the pair of intake ports. The fuel injector is configured to spray fuel toward the piston.
The engine body can comprise a cylinder body connected to a cylinder head, and wherein the fuel injector is located between the induction system and a plane extending laterally from the connection between the cylinder body and the cylinder head.